security/tomoyo/realpath.c - linux-mtk - Git at Google

 /*
  * security/tomoyo/realpath.c
  *
  * Get the canonicalized absolute pathnames. The basis for TOMOYO.
  *
  * Copyright (C) 2005-2009  NTT DATA CORPORATION
  *
  * Version: 2.2.0   2009/04/01
  *
  */

 #include <linux/types.h>
 #include <linux/mount.h>
 #include <linux/mnt_namespace.h>
 #include <linux/fs_struct.h>
 #include <linux/hash.h>
 #include <linux/magic.h>
 #include "common.h"

 /**
  * tomoyo_encode: Convert binary string to ascii string.
  *
  * @buffer:  Buffer for ASCII string.
  * @buflen:  Size of @buffer.
  * @str:     Binary string.
  *
  * Returns 0 on success, -ENOMEM otherwise.
  */
 int tomoyo_encode(char *buffer, int buflen, const char *str)
 {
 	while (1) {
 		const unsigned char c = *(unsigned char *) str++;

 		if (tomoyo_is_valid(c)) {
 			if (--buflen <= 0)
 				break;
 			*buffer++ = (char) c;
 			if (c != '\\')
 				continue;
 			if (--buflen <= 0)
 				break;
 			*buffer++ = (char) c;
 			continue;
 		}
 		if (!c) {
 			if (--buflen <= 0)
 				break;
 			*buffer = '\0';
 			return 0;
 		}
 		buflen -= 4;
 		if (buflen <= 0)
 			break;
 		*buffer++ = '\\';
 		*buffer++ = (c >> 6) + '0';
 		*buffer++ = ((c >> 3) & 7) + '0';
 		*buffer++ = (c & 7) + '0';
 	}
 	return -ENOMEM;
 }

 /**
  * tomoyo_realpath_from_path2 - Returns realpath(3) of the given dentry but ignores chroot'ed root.
  *
  * @path:        Pointer to "struct path".
  * @newname:     Pointer to buffer to return value in.
  * @newname_len: Size of @newname.
  *
  * Returns 0 on success, negative value otherwise.
  *
  * If dentry is a directory, trailing '/' is appended.
  * Characters out of 0x20 < c < 0x7F range are converted to
  * \ooo style octal string.
  * Character \ is converted to \\ string.
  */
 int tomoyo_realpath_from_path2(struct path *path, char *newname,
 			       int newname_len)
 {
 	int error = -ENOMEM;
 	struct dentry *dentry = path->dentry;
 	char *sp;

 	if (!dentry || !path->mnt || !newname || newname_len <= 2048)
 		return -EINVAL;
 	if (dentry->d_op && dentry->d_op->d_dname) {
 		/* For "socket:[\$]" and "pipe:[\$]". */
 		static const int offset = 1536;
 		sp = dentry->d_op->d_dname(dentry, newname + offset,
 					   newname_len - offset);
 	} else {
 		struct path ns_root = {.mnt = NULL, .dentry = NULL};

 		spin_lock(&dcache_lock);
 		/* go to whatever namespace root we are under */
 		sp = __d_path(path, &ns_root, newname, newname_len);
 		spin_unlock(&dcache_lock);
 		/* Prepend "/proc" prefix if using internal proc vfs mount. */
 		if (!IS_ERR(sp) && (path->mnt->mnt_flags & MNT_INTERNAL) &&
 		    (path->mnt->mnt_sb->s_magic == PROC_SUPER_MAGIC)) {
 			sp -= 5;
 			if (sp >= newname)
 				memcpy(sp, "/proc", 5);
 			else
 				sp = ERR_PTR(-ENOMEM);
 		}
 	}
 	if (IS_ERR(sp))
 		error = PTR_ERR(sp);
 	else
 		error = tomoyo_encode(newname, sp - newname, sp);
 	/* Append trailing '/' if dentry is a directory. */
 	if (!error && dentry->d_inode && S_ISDIR(dentry->d_inode->i_mode)
 	    && *newname) {
 		sp = newname + strlen(newname);
 		if (*(sp - 1) != '/') {
 			if (sp < newname + newname_len - 4) {
 				*sp++ = '/';
 				*sp = '\0';
 			} else {
 				error = -ENOMEM;
 			}
 		}
 	}
 	if (error)
 		printk(KERN_WARNING "tomoyo_realpath: Pathname too long.\n");
 	return error;
 }

 /**
  * tomoyo_realpath_from_path - Returns realpath(3) of the given pathname but ignores chroot'ed root.
  *
  * @path: Pointer to "struct path".
  *
  * Returns the realpath of the given @path on success, NULL otherwise.
  *
  * These functions use kzalloc(), so the caller must call kfree()
  * if these functions didn't return NULL.
  */
 char *tomoyo_realpath_from_path(struct path *path)
 {
 	char *buf = kzalloc(sizeof(struct tomoyo_page_buffer), GFP_KERNEL);

 	BUILD_BUG_ON(sizeof(struct tomoyo_page_buffer)
 		     <= TOMOYO_MAX_PATHNAME_LEN - 1);
 	if (!buf)
 		return NULL;
 	if (tomoyo_realpath_from_path2(path, buf,
 				       TOMOYO_MAX_PATHNAME_LEN - 1) == 0)
 		return buf;
 	kfree(buf);
 	return NULL;
 }

 /**
  * tomoyo_realpath - Get realpath of a pathname.
  *
  * @pathname: The pathname to solve.
  *
  * Returns the realpath of @pathname on success, NULL otherwise.
  */
 char *tomoyo_realpath(const char *pathname)
 {
 	struct path path;

 	if (pathname && kern_path(pathname, LOOKUP_FOLLOW, &path) == 0) {
 		char *buf = tomoyo_realpath_from_path(&path);
 		path_put(&path);
 		return buf;
 	}
 	return NULL;
 }

 /**
  * tomoyo_realpath_nofollow - Get realpath of a pathname.
  *
  * @pathname: The pathname to solve.
  *
  * Returns the realpath of @pathname on success, NULL otherwise.
  */
 char *tomoyo_realpath_nofollow(const char *pathname)
 {
 	struct path path;

 	if (pathname && kern_path(pathname, 0, &path) == 0) {
 		char *buf = tomoyo_realpath_from_path(&path);
 		path_put(&path);
 		return buf;
 	}
 	return NULL;
 }

 /* Memory allocated for non-string data. */
 static atomic_t tomoyo_policy_memory_size;
 /* Quota for holding policy. */
 static unsigned int tomoyo_quota_for_policy;

 /**
  * tomoyo_memory_ok - Check memory quota.
  *
  * @ptr: Pointer to allocated memory.
  *
  * Returns true on success, false otherwise.
  *
  * Caller holds tomoyo_policy_lock.
  * Memory pointed by @ptr will be zeroed on success.
  */
 bool tomoyo_memory_ok(void *ptr)
 {
 	int allocated_len = ptr ? ksize(ptr) : 0;
 	atomic_add(allocated_len, &tomoyo_policy_memory_size);
 	if (ptr && (!tomoyo_quota_for_policy ||
 		    atomic_read(&tomoyo_policy_memory_size)
 		    <= tomoyo_quota_for_policy)) {
 		memset(ptr, 0, allocated_len);
 		return true;
 	}
 	printk(KERN_WARNING "ERROR: Out of memory "
 	       "for tomoyo_alloc_element().\n");
 	if (!tomoyo_policy_loaded)
 		panic("MAC Initialization failed.\n");
 	return false;
 }

 /**
  * tomoyo_memory_free - Free memory for elements.
  *
  * @ptr:  Pointer to allocated memory.
  */
 void tomoyo_memory_free(void *ptr)
 {
 	atomic_sub(ksize(ptr), &tomoyo_policy_memory_size);
 	kfree(ptr);
 }

 /*
  * tomoyo_name_list is used for holding string data used by TOMOYO.
  * Since same string data is likely used for multiple times (e.g.
  * "/lib/libc-2.5.so"), TOMOYO shares string data in the form of
  * "const struct tomoyo_path_info *".
  */
 struct list_head tomoyo_name_list[TOMOYO_MAX_HASH];
 /* Lock for protecting tomoyo_name_list . */
 DEFINE_MUTEX(tomoyo_name_list_lock);

 /**
  * tomoyo_get_name - Allocate permanent memory for string data.
  *
  * @name: The string to store into the permernent memory.
  *
  * Returns pointer to "struct tomoyo_path_info" on success, NULL otherwise.
  */
 const struct tomoyo_path_info *tomoyo_get_name(const char *name)
 {
 	struct tomoyo_name_entry *ptr;
 	unsigned int hash;
 	int len;
 	int allocated_len;
 	struct list_head *head;

 	if (!name)
 		return NULL;
 	len = strlen(name) + 1;
 	hash = full_name_hash((const unsigned char *) name, len - 1);
 	head = &tomoyo_name_list[hash_long(hash, TOMOYO_HASH_BITS)];
 	mutex_lock(&tomoyo_name_list_lock);
 	list_for_each_entry(ptr, head, list) {
 		if (hash != ptr->entry.hash || strcmp(name, ptr->entry.name))
 			continue;
 		atomic_inc(&ptr->users);
 		goto out;
 	}
 	ptr = kzalloc(sizeof(*ptr) + len, GFP_KERNEL);
 	allocated_len = ptr ? ksize(ptr) : 0;
 	if (!ptr || (tomoyo_quota_for_policy &&
 		     atomic_read(&tomoyo_policy_memory_size) + allocated_len
 		     > tomoyo_quota_for_policy)) {
 		kfree(ptr);
 		printk(KERN_WARNING "ERROR: Out of memory "
 		       "for tomoyo_get_name().\n");
 		if (!tomoyo_policy_loaded)
 			panic("MAC Initialization failed.\n");
 		ptr = NULL;
 		goto out;
 	}
 	atomic_add(allocated_len, &tomoyo_policy_memory_size);
 	ptr->entry.name = ((char *) ptr) + sizeof(*ptr);
 	memmove((char *) ptr->entry.name, name, len);
 	atomic_set(&ptr->users, 1);
 	tomoyo_fill_path_info(&ptr->entry);
 	list_add_tail(&ptr->list, head);
  out:
 	mutex_unlock(&tomoyo_name_list_lock);
 	return ptr ? &ptr->entry : NULL;
 }

 /**
  * tomoyo_realpath_init - Initialize realpath related code.
  */
 void __init tomoyo_realpath_init(void)
 {
 	int i;

 	BUILD_BUG_ON(TOMOYO_MAX_PATHNAME_LEN > PATH_MAX);
 	for (i = 0; i < TOMOYO_MAX_HASH; i++)
 		INIT_LIST_HEAD(&tomoyo_name_list[i]);
 	INIT_LIST_HEAD(&tomoyo_kernel_domain.acl_info_list);
 	tomoyo_kernel_domain.domainname = tomoyo_get_name(TOMOYO_ROOT_NAME);
 	/*
 	 * tomoyo_read_lock() is not needed because this function is
 	 * called before the first "delete" request.
 	 */
 	list_add_tail_rcu(&tomoyo_kernel_domain.list, &tomoyo_domain_list);
 	if (tomoyo_find_domain(TOMOYO_ROOT_NAME) != &tomoyo_kernel_domain)
 		panic("Can't register tomoyo_kernel_domain");
 }

 /**
  * tomoyo_read_memory_counter - Check for memory usage in bytes.
  *
  * @head: Pointer to "struct tomoyo_io_buffer".
  *
  * Returns memory usage.
  */
 int tomoyo_read_memory_counter(struct tomoyo_io_buffer *head)
 {
 	if (!head->read_eof) {
 		const unsigned int policy
 			= atomic_read(&tomoyo_policy_memory_size);
 		char buffer[64];

 		memset(buffer, 0, sizeof(buffer));
 		if (tomoyo_quota_for_policy)
 			snprintf(buffer, sizeof(buffer) - 1,
 				 "   (Quota: %10u)",
 				 tomoyo_quota_for_policy);
 		else
 			buffer[0] = '\0';
 		tomoyo_io_printf(head, "Policy:  %10u%s\n", policy, buffer);
 		tomoyo_io_printf(head, "Total:   %10u\n", policy);
 		head->read_eof = true;
 	}
 	return 0;
 }

 /**
  * tomoyo_write_memory_quota - Set memory quota.
  *
  * @head: Pointer to "struct tomoyo_io_buffer".
  *
  * Returns 0.
  */
 int tomoyo_write_memory_quota(struct tomoyo_io_buffer *head)
 {
 	char *data = head->write_buf;
 	unsigned int size;

 	if (sscanf(data, "Policy: %u", &size) == 1)
 		tomoyo_quota_for_policy = size;
 	return 0;
 }
	/*
	* security/tomoyo/realpath.c
	*
	* Get the canonicalized absolute pathnames. The basis for TOMOYO.
	*
	* Copyright (C) 2005-2009 NTT DATA CORPORATION
	*
	* Version: 2.2.0 2009/04/01
	*
	*/

	#include <linux/types.h>
	#include <linux/mount.h>
	#include <linux/mnt_namespace.h>
	#include <linux/fs_struct.h>
	#include <linux/hash.h>
	#include <linux/magic.h>
	#include "common.h"

	/**
	* tomoyo_encode: Convert binary string to ascii string.
	*
	* @buffer: Buffer for ASCII string.
	* @buflen: Size of @buffer.
	* @str: Binary string.
	*
	* Returns 0 on success, -ENOMEM otherwise.
	*/
	int tomoyo_encode(char buffer, int buflen, const char str)
	{
	while (1) {
	const unsigned char c = (unsigned char ) str++;

	if (tomoyo_is_valid(c)) {
	if (--buflen <= 0)
	break;
	*buffer++ = (char) c;
	if (c != '\\')
	continue;
	if (--buflen <= 0)
	break;
	*buffer++ = (char) c;
	continue;
	}
	if (!c) {
	if (--buflen <= 0)
	break;
	*buffer = '\0';
	return 0;
	}
	buflen -= 4;
	if (buflen <= 0)
	break;
	*buffer++ = '\\';
	*buffer++ = (c >> 6) + '0';
	*buffer++ = ((c >> 3) & 7) + '0';
	*buffer++ = (c & 7) + '0';
	}
	return -ENOMEM;
	}

	/**
	* tomoyo_realpath_from_path2 - Returns realpath(3) of the given dentry but ignores chroot'ed root.
	*
	* @path: Pointer to "struct path".
	* @newname: Pointer to buffer to return value in.
	* @newname_len: Size of @newname.
	*
	* Returns 0 on success, negative value otherwise.
	*
	* If dentry is a directory, trailing '/' is appended.
	* Characters out of 0x20 < c < 0x7F range are converted to
	* \ooo style octal string.
	* Character \ is converted to \\ string.
	*/
	int tomoyo_realpath_from_path2(struct path path, char newname,
	int newname_len)
	{
	int error = -ENOMEM;
	struct dentry *dentry = path->dentry;
	char *sp;

	if (!dentry \|\| !path->mnt \|\| !newname \|\| newname_len <= 2048)
	return -EINVAL;
	if (dentry->d_op && dentry->d_op->d_dname) {
	/* For "socket:[\$]" and "pipe:[\$]". */
	static const int offset = 1536;
	sp = dentry->d_op->d_dname(dentry, newname + offset,
	newname_len - offset);
	} else {
	struct path ns_root = {.mnt = NULL, .dentry = NULL};

	spin_lock(&dcache_lock);
	/* go to whatever namespace root we are under */
	sp = __d_path(path, &ns_root, newname, newname_len);
	spin_unlock(&dcache_lock);
	/* Prepend "/proc" prefix if using internal proc vfs mount. */
	if (!IS_ERR(sp) && (path->mnt->mnt_flags & MNT_INTERNAL) &&
	(path->mnt->mnt_sb->s_magic == PROC_SUPER_MAGIC)) {
	sp -= 5;
	if (sp >= newname)
	memcpy(sp, "/proc", 5);
	else
	sp = ERR_PTR(-ENOMEM);
	}
	}
	if (IS_ERR(sp))
	error = PTR_ERR(sp);
	else
	error = tomoyo_encode(newname, sp - newname, sp);
	/* Append trailing '/' if dentry is a directory. */
	if (!error && dentry->d_inode && S_ISDIR(dentry->d_inode->i_mode)
	&& *newname) {
	sp = newname + strlen(newname);
	if (*(sp - 1) != '/') {
	if (sp < newname + newname_len - 4) {
	*sp++ = '/';
	*sp = '\0';
	} else {
	error = -ENOMEM;
	}
	}
	}
	if (error)
	printk(KERN_WARNING "tomoyo_realpath: Pathname too long.\n");
	return error;
	}

	/**
	* tomoyo_realpath_from_path - Returns realpath(3) of the given pathname but ignores chroot'ed root.
	*
	* @path: Pointer to "struct path".
	*
	* Returns the realpath of the given @path on success, NULL otherwise.
	*
	* These functions use kzalloc(), so the caller must call kfree()
	* if these functions didn't return NULL.
	*/
	char tomoyo_realpath_from_path(struct path path)
	{
	char *buf = kzalloc(sizeof(struct tomoyo_page_buffer), GFP_KERNEL);

	BUILD_BUG_ON(sizeof(struct tomoyo_page_buffer)
	<= TOMOYO_MAX_PATHNAME_LEN - 1);
	if (!buf)
	return NULL;
	if (tomoyo_realpath_from_path2(path, buf,
	TOMOYO_MAX_PATHNAME_LEN - 1) == 0)
	return buf;
	kfree(buf);
	return NULL;
	}

	/**
	* tomoyo_realpath - Get realpath of a pathname.
	*
	* @pathname: The pathname to solve.
	*
	* Returns the realpath of @pathname on success, NULL otherwise.
	*/
	char tomoyo_realpath(const char pathname)
	{
	struct path path;

	if (pathname && kern_path(pathname, LOOKUP_FOLLOW, &path) == 0) {
	char *buf = tomoyo_realpath_from_path(&path);
	path_put(&path);
	return buf;
	}
	return NULL;
	}

	/**
	* tomoyo_realpath_nofollow - Get realpath of a pathname.
	*
	* @pathname: The pathname to solve.
	*
	* Returns the realpath of @pathname on success, NULL otherwise.
	*/
	char tomoyo_realpath_nofollow(const char pathname)
	{
	struct path path;

	if (pathname && kern_path(pathname, 0, &path) == 0) {
	char *buf = tomoyo_realpath_from_path(&path);
	path_put(&path);
	return buf;
	}
	return NULL;
	}

	/* Memory allocated for non-string data. */
	static atomic_t tomoyo_policy_memory_size;
	/* Quota for holding policy. */
	static unsigned int tomoyo_quota_for_policy;

	/**
	* tomoyo_memory_ok - Check memory quota.
	*
	* @ptr: Pointer to allocated memory.
	*
	* Returns true on success, false otherwise.
	*
	* Caller holds tomoyo_policy_lock.
	* Memory pointed by @ptr will be zeroed on success.
	*/
	bool tomoyo_memory_ok(void *ptr)
	{
	int allocated_len = ptr ? ksize(ptr) : 0;
	atomic_add(allocated_len, &tomoyo_policy_memory_size);
	if (ptr && (!tomoyo_quota_for_policy \|\|
	atomic_read(&tomoyo_policy_memory_size)
	<= tomoyo_quota_for_policy)) {
	memset(ptr, 0, allocated_len);
	return true;
	}
	printk(KERN_WARNING "ERROR: Out of memory "
	"for tomoyo_alloc_element().\n");
	if (!tomoyo_policy_loaded)
	panic("MAC Initialization failed.\n");
	return false;
	}

	/**
	* tomoyo_memory_free - Free memory for elements.
	*
	* @ptr: Pointer to allocated memory.
	*/
	void tomoyo_memory_free(void *ptr)
	{
	atomic_sub(ksize(ptr), &tomoyo_policy_memory_size);
	kfree(ptr);
	}

	/*
	* tomoyo_name_list is used for holding string data used by TOMOYO.
	* Since same string data is likely used for multiple times (e.g.
	* "/lib/libc-2.5.so"), TOMOYO shares string data in the form of
	* "const struct tomoyo_path_info *".
	*/
	struct list_head tomoyo_name_list[TOMOYO_MAX_HASH];
	/* Lock for protecting tomoyo_name_list . */
	DEFINE_MUTEX(tomoyo_name_list_lock);

	/**
	* tomoyo_get_name - Allocate permanent memory for string data.
	*
	* @name: The string to store into the permernent memory.
	*
	* Returns pointer to "struct tomoyo_path_info" on success, NULL otherwise.
	*/
	const struct tomoyo_path_info tomoyo_get_name(const char name)
	{
	struct tomoyo_name_entry *ptr;
	unsigned int hash;
	int len;
	int allocated_len;
	struct list_head *head;

	if (!name)
	return NULL;
	len = strlen(name) + 1;
	hash = full_name_hash((const unsigned char *) name, len - 1);
	head = &tomoyo_name_list[hash_long(hash, TOMOYO_HASH_BITS)];
	mutex_lock(&tomoyo_name_list_lock);
	list_for_each_entry(ptr, head, list) {
	if (hash != ptr->entry.hash \|\| strcmp(name, ptr->entry.name))
	continue;
	atomic_inc(&ptr->users);
	goto out;
	}
	ptr = kzalloc(sizeof(*ptr) + len, GFP_KERNEL);
	allocated_len = ptr ? ksize(ptr) : 0;
	if (!ptr \|\| (tomoyo_quota_for_policy &&
	atomic_read(&tomoyo_policy_memory_size) + allocated_len
	> tomoyo_quota_for_policy)) {
	kfree(ptr);
	printk(KERN_WARNING "ERROR: Out of memory "
	"for tomoyo_get_name().\n");
	if (!tomoyo_policy_loaded)
	panic("MAC Initialization failed.\n");
	ptr = NULL;
	goto out;
	}
	atomic_add(allocated_len, &tomoyo_policy_memory_size);
	ptr->entry.name = ((char ) ptr) + sizeof(ptr);
	memmove((char *) ptr->entry.name, name, len);
	atomic_set(&ptr->users, 1);
	tomoyo_fill_path_info(&ptr->entry);
	list_add_tail(&ptr->list, head);
	out:
	mutex_unlock(&tomoyo_name_list_lock);
	return ptr ? &ptr->entry : NULL;
	}

	/**
	* tomoyo_realpath_init - Initialize realpath related code.
	*/
	void __init tomoyo_realpath_init(void)
	{
	int i;

	BUILD_BUG_ON(TOMOYO_MAX_PATHNAME_LEN > PATH_MAX);
	for (i = 0; i < TOMOYO_MAX_HASH; i++)
	INIT_LIST_HEAD(&tomoyo_name_list[i]);
	INIT_LIST_HEAD(&tomoyo_kernel_domain.acl_info_list);
	tomoyo_kernel_domain.domainname = tomoyo_get_name(TOMOYO_ROOT_NAME);
	/*
	* tomoyo_read_lock() is not needed because this function is
	* called before the first "delete" request.
	*/
	list_add_tail_rcu(&tomoyo_kernel_domain.list, &tomoyo_domain_list);
	if (tomoyo_find_domain(TOMOYO_ROOT_NAME) != &tomoyo_kernel_domain)
	panic("Can't register tomoyo_kernel_domain");
	}

	/**
	* tomoyo_read_memory_counter - Check for memory usage in bytes.
	*
	* @head: Pointer to "struct tomoyo_io_buffer".
	*
	* Returns memory usage.
	*/
	int tomoyo_read_memory_counter(struct tomoyo_io_buffer *head)
	{
	if (!head->read_eof) {
	const unsigned int policy
	= atomic_read(&tomoyo_policy_memory_size);
	char buffer[64];

	memset(buffer, 0, sizeof(buffer));
	if (tomoyo_quota_for_policy)
	snprintf(buffer, sizeof(buffer) - 1,
	" (Quota: %10u)",
	tomoyo_quota_for_policy);
	else
	buffer[0] = '\0';
	tomoyo_io_printf(head, "Policy: %10u%s\n", policy, buffer);
	tomoyo_io_printf(head, "Total: %10u\n", policy);
	head->read_eof = true;
	}
	return 0;
	}

	/**
	* tomoyo_write_memory_quota - Set memory quota.
	*
	* @head: Pointer to "struct tomoyo_io_buffer".
	*
	* Returns 0.
	*/
	int tomoyo_write_memory_quota(struct tomoyo_io_buffer *head)
	{
	char *data = head->write_buf;
	unsigned int size;

	if (sscanf(data, "Policy: %u", &size) == 1)
	tomoyo_quota_for_policy = size;
	return 0;
	}